I had Covid for the fourth time in December 2023, and I came out of that with Long Covid. One of my symptoms was a daily low-grade fever (anywhere from 99 to 101), increasing with exposure to heat and with exertion. I finally was tested at Mayo Clinic, and it turns out I don't sweat much at all any more, which explains why my temperature goes up. It's not technically a fever at all; it's technically just an elevated body temperature. For me it has become a sign that I need to rest and let my body cool down - get into a cooler environment and sit quietly for a while. Fortunately it does seem to be improving very slowly. I haven't seen a temp in the 100s for several months.